On October 3, 1967, Col William John Knight set a world aircraft speed record for manned aircraft by piloting the X-15A-2 (#56-6671) to 4,520 miles per hour (7,274 km/h) (Mach 6.70), a record that still stands today. During 16 flights in the aircraft, Knight also became one of only five pilots to earn their Astronaut Wings by flying an airplane in space, reaching an altitude of 280,500 feet (85,500 m). This design is inspired by that same aircraft.